New 5-cholestene derivatives and preparation thereof

ABSTRACT

New 5-cholesten-3 Beta ,24,25- or 3 Beta ,25,26-triol and esters thereof, which are valuable intermediates for the production of active vitamin D3, are provided by a process wherein the protected 3 Beta -hydroxy-5,24- or -5,25-cholestadiene is treated with osmium tetroxide to form osmate ester thereof and the latter is decomposed to the corresponding 24,25- or 25,26-dihydroxy compound, and, if necessary, the 3 Beta -hydroxy-protected group thereof is splitt off to produce the 5-cholesten-triol and one or more of the hydroxy groups of the resulting products are esterified with acylating reagent.

United States Patent [191 Ikekawa et al. Dec. 23, 1975 NEW S-CHOLESTENE DERIVATIVES AND [56] References Cited PREPARATION THEREOF UNITED STATES PATENTS [75] Inventors: Nobuo lkekawa; Masuo Morisaki; 3,715,374 2/1973 De Luca 260/3972 Julieta Rubio Lightbourn, all of 3,739,001 6/1973 De Luca 260/3972 T k M3530 s ki Komae, l f 3,822,254 7/1974 Patridge, Jr. et al. 260/3972 Ja an 0 Primary Examiner-Elbert L. Roberts Asslgnee: E1531 w -v Japan Attorney, Agent, or FirmWenderoth, Lind & Ponack [22] Filed: Jan. 6, 1975 21 l N [57] ABSTRACT App. 0.. 538,772 New 5-cholesten-3B,24,25- or 3B,25,26-triol and es- Related US. Application Data ters thereof, which are valuable intermediates for the [63] Continuation-impart of Ser. No. 446,108, Feb. 26, production of active vitamin D3 are provided by a 1974 process wherein the protected 3B-hydroxy-5,24- or -5,25-cholestadiene is treated with osmium tetroxide [30] For i A li ati P i it D to form osmate ester thereof and the latter is decom- Mar. 2, 1973 Japan 48-24261 posed to the corresponding 24,25 or zszfidihydmxy M 2, 1973 compound, and, if necessary, the 3/3-hydroxyat Japan 48 24262 protected group thereof is splitt off to produce the 5- 52 us. Cl and one 0f the hydmxy gmups E51} m. cm ffiffffieifi /fifi of the resulting products are esterified with acylafing 58 Field of Search 260/3972 reagent- 9 Claims, No Drawings NEW S-CHOLESTENE DERIVATIVES AND PREPARATION THEREOF Thisis a continuation-in-part application of Serial No. 446,108 filed February 26, 1974.

This invention relates to a new S-cholestene derivatives and a process for the preparation thereof.

The new -ch0lestene derivatives according to the present invention are represented by the following formula:

wherein R is hydrogen, alkanoyl, aroyl or hydroxyprotecting group; and each of R R, R and R is hydrogen, alkanoyl, aroyl or trialkylsilyl.

Through out the specification and claims, the term alkanoyl refers to the groups derived'from lower propionyl,

aliphatic carboxylic acid, such ,as acetyl, butyryl and the like; the term aroyl. refers to the groups derived from aromatic carboxylic acid, such as benzoyl or substituted benzoyl; and finally, the term hydroxy-protecting group refers to any of the substituents usually used for the protection of hydroxy group on steroid nucleus. Representatives of such hydroxyprotecting groups include aliphatic or aromatic hydrocarbon residue such' as methyl, ethyl and benzyl, and alkanoyl or aroyl such as aforementioned.

The followings are the representatives of the new 5 -cholestene derivatives intended in the present invention: l

5-cholesten-3,8,24,2S-triol,

5-cholesten-3fi,24,25-triol 3-acetate,

5-cholesten-3B,24,25-triol 3-benzoate, 5 cholesten-3B,24,25-triol 3,24,25-triacetate 5-cholesten 3',8,24,25-triol 3,24-diacetate,

5-cholesten-3B,24,25-triol 3,8,24-dibenzoate,

5=cholesten-3B,24,25-triol 3B,24,25-tribenzoate,

2 5-tntmethylsilyloxy- 5-cholesten-3/3,24R-diol dibenzoa e,

-tritmethylsilyloxy- 5-cholsten-3B,24S-diol dibenzoa e,

SB-methoxy-S-cholesten-24,25-diol,

5-cholesten-3,B,25,26-triol,

5-cholesten3B, ,26-triol 3-acetate.

5-cholesten-3B,25,26-triol 3benzoate,

5-cholesten-3B,25,26-triol 3,25,26-tripropionate and 2 SB-methoxy-S-cholesten-Z5,26-diol. 5-Cholesten-3B,24,25-(or -3B,25,26-)triol and esters thereof of the aforementioned formula Ia or lb of the present invention can easily be converted to 5 24,25-(or 25,26-)-dihydroxycholecalciferol and esters thereof by the reaction sequence of:

i. bromination to form 7-bromo derivative;

ii. dehydrobromination to form 7-dehydro derivative;

and

iii. ultraviolet ray irradiation to form the dihydroxycholecalciferol.

It is known that the dihydroxycholecalciferols are the metabolite of cholecalciferol, i.e., vitamin D and ones of the active forms of vitamin D They have been obtained only in a minute amount by a troublesome solation procedure from blood or tissue of the animals which had been administered a large amount of cholecalciferol, and their production by sole chemical method is as yet unknown. Consequently, the new compounds of the present invention are valuable as the intermediate for the commercial production of 24,25-(or 25,26-)dihydroxycholecalciferol.

BB-Protected-hydroxy-S,24(or enes having the respective formula:

Ilia III:

group, is the starting material employed for the production of the compounds of the aforementioned formula la or lb in accordance with the present invention. Some of the compounds of the formulae Ila and llb are known, while others may be produced according to the known methods. For instance, 5,24-cholestadien-3 [3-01 acetate of the formula Ila where R acetyl, i.e., desmosterol acetate, and 5,25-cholestadien-3B-ol acetatei of the formula IIb where R acetyl, i.e., 25-dehydrocholesterol acetate, may simultaneously be produced in an admixture, when 5-cholesten-3B,25-diol S-acetate, i.e., 25-hydroxylcholesterol acetate is treated with phosphorous oxychloride. The resulting 5,24-diene and 5,25-diene compounds may separately be obtained from the reaction mixture by preparative thin-layer -5 ,25- )cholestadiwherein R in the both cases is hydroxy-protecting temperature or below, preferably at room temperature, and for several hours to a few days. There is thus obtained the osmate ester wherein a molecule of osmium tetroxide has entered into the double bond between 24- and 25- or 25- and 26-positions of the starting material.

After removal of the solvent, the resulting osmate ester is treated with a reagent capable of decomposing the osmate ester. Any of the reagents known in the arts to decompose osmate ester may be utilized for this purpose. Representatives of the reagent include pyridine-aqueous alkali bisulfite; ethanol-aqueous alkali sulfite; mannitol-aqueous alkali hydroxide; zinc-acetic acid; concentrated hydrochloric acid; potassium chlo-' rate-sulfuric acid; chromic acid-acetic acid; formaldehyde-aqueous alkali hydroxide; hydrogen sulfide and the like.

As the result of the decomposition of the osmate ester, there is obtained 3B-protected-hydroxy-5-cholesten-24,25-(or -25,26-)dio1 or corresponding 3B-free hydroxy steroid, depending upon the reagent and reaction condition employed. Each of the steroid products may be isolated from the reaction mixture by a conventional isolation procedure.

3B-Hydroxy-protecting group of the resulting 3B- protected-hydroxy steroids, if necessary, is split off by a conventional procedure such as an alkaline hydrolysis to give the corresponding 3,8-free hydroxy compound,

EXAMPLE 1 One gram of desmosterol acetate (or 5,24-cholestadien-3B-ol) and 589 mg. of osmium tetroxide were suspended in 40 ml. of dry ether. The resulting suspension was stirred at room temperature for 19 hours. After removal of the ether by distillation, there were added 60 ml. of pyridine, 45 ml. of water and 2 g. of

sodium bisulfite, and the mixture was stirred at room temperature for further 19 hours. The resulting reaction mixture was extracted with ether. The etheral extract was washed successively with a dilute hydrochloric acid and water, dried on anhydrous sodium sulfate and evaporated up to dry. 1.008 g. of -cholesten-3B,24,25trio1 3B-acetate were obtained, which amounted to 93.4% of the theoretical yield.

In a silica gel thin-layer chromatography, the product gave a single spot. MP: 152C. (from acetone).

Elementary analysis:

C ,,H O (molecular weight of 460.67)

Calculated 75.60 10.50 Found 75.34 10.56

EXAMPLE 2 100 mg. of 5-cholesten-3B,24,25-triol 3B-acetate obtained in the preceding Example were dissolved in a mixture of 0.3 ml. of pyridine and 0.3 ml. of acetic anhydride. After standing overnight, the reaction mixture was poured onto ice-water. The resulting crystalline substance was recovered by filtration, and recrystallized from n-hexane. There was obtained 5-cholesten-3,8,24,25,-triol 313,24-diacetate having the melting point of 167.5C. to 168C. (from n-hexane).

- Elementary analysis:

C H O (molecular weight of 502.71)

1n the above, '5 singlet; d doublet: and m mulliplet.

EXAMPLE 3 To 20 m1. of dry ether, there were introduced 500 mg. of 5,25-cholestadien-3B-ol acetate and 295 mg. of osmium tetroxide. The resulting reaction mixture was stirred at room temperature for 24 hours. After removal of the ether, 30 m1. of pyridine, 22 ml. of water and 1 g. of sodium bisulfite were added successively to the residue, and the mixture was stirred at room temperature for 19 hours. The reaction mixture was extracted with ether, and the etheral extract was washed with a dilute hydrochloric acid followed by water, dried on anhydrous sodium sulfate and the solvent was removed by distillation. Crude reaction product thus obtained was purified by a thin-layer chromatography on a silica gel plate, eluting with a mixture of benzene and ethyl acetate (10 1 5 1). There were obtained 380.6 mg. of 5-cholesten-3B,25,26-triol 3B-acetate amounting to 70.5% of the theoretical yield. MP: 169 171C. (from ethanol water).

Elementary analysis:

CO 3.41 2 H s C26-CH2 4.60 l H m" C--3H 5.35 1 H m C6-H In the above, '5 singlet; m mulliplet.

EXAMPLE 4 To 20 ml. of dry ether, there were introduced 500 mg. of 5,25-cholestadien-3B-ol acetate and 295 mg. of osmium tetroxide. The resulting mixture was stirred at room temperature for 24 hours. After removal of the ether, 30 ml. of ethanol, 48 ml. of water and 1.47 g. of sodium sulfite were added to the residue, and the mixture was refluxed for 3 hours. The reaction mixture was extracted with ether, and the etheral extract was washed successively with a dilute hydrochloric acid and water, dried on anhydrous sodium sulfate and the solvent was distilled off. The resulting crude reaction product was purified by the chromatography same as that mentioned in Example 3. There were obtained 336.3 mg. of 5-cho1esten-3B,25,26-triol 3B-acetate amounting to 62.3% of the theoretical yield.

EXAMPLE 5 1100 mg. of 5'cholesten-3,8,24,25-trio1 3B-acetate were refluxed in 5 ml. of methanolic solution of 5% EXAMPLE 6 100 mg. of -cholesten-3B,25,26-trio1 3B-acetate were hydrolyzed with 5 ml. of 5% potassium hydroxide solution in methanol using the essentially same manner as in the preceding EXAMPLE 5. There were thus obtained 90 mg. of 5-cholesten-3B,25,26-triol as white powder melting at 180 192C. (from dimethyl ketone).

EXAMPLE 7 433 mg. of 5cholesten-38,24,25-triol were treated overnight with 1.0 ml. of benzoyl chloride in 2 ml. of dry pyridine at room temperature. The reaction mixture was poured into ice-water and extracted with ether. The ethereal layer was concentrated under reduced pressure. The resulting crude produce was chromatographed on a column which was packed with g. of silica gel, and purified by using hexane-benzene (1:1) as a solvent for elution. The elute was recovered as aliquot of fractions, each containing 50 ml.

The fraction Nos. 7-10 were combined. By removing the solvent from the combined fractions, there were obtained 148 mg of less polar 5-cholesten-3,8,24R,25- triol tribenzoate as crystals having the melting point of 173C to 174C. (from acetone). I

From the fraction Nos. 15-23, there were obtained, after the removal of the solvent, 132 mg. of more polar 5-cholesten-3B,24S, -triol tribenzoate as an amorphous powder.

457 mg of 5-cholesten-3B,24,25-triol 3,24-diben'zoate were obtained from the fractions which were eluted with benzene-ethyl acetate (9:1

EXAMPLES 483 mg of 5-cholesten-3B,24,25-triol 3,8,24-dibenzoate were dissolved into 2 ml of trimethylsilyl imidazole. The reaction mixture was heated at 90C for 1 hour, and then extracted with hexane. The extract was washed with water, and dried on sodium sulfate. By distilling off the solvent, 543 mg. of the crude product were obtained. The crude product was purified by chromatography on a column which was packed with silica gel (SiO and eluted with hexane-benzene (lz l) to recover the fractions. I

The fractions were again chromatographed on silica gel column, and eluted with hexane-benzane (7:3). The

- elute was divided every 50 ml.

The fraction Nos. 9-1 1 were combined. By removing the solvent from the combined fractions, there were obtained less polar 25-trimethylsi1yloxy-5-cholesten- 3B,24R-diol dibenzoate as white crystals melting at 156C. (from hexane).

ln'the same way, there were obtained, from the fraction Nos. 16-19, more polar 25-trimethylsilyloxy-5- cholesten-3,B,24S-diol dibenzoate as white crystals having the melting point of 159 160C. (from hexane).

What is claimed is: l. 5-Cholestene derivatives represented by the formula: I

wherein R is hydrogen, alkanoyl, aroyl or hydroxyprotecting group, and each of R"-, R, R and R is hydrogen, alkanoyl, aroyl or trialkylsilyl.

.. S-Cholesten-35,24,25-triol 3-acetate.

. 5-Cho1esten-3[3,24,25-triol 3,24-diacetate.

. 5-Cholesten-3B,25,26-triol 3acetate.

. 5Cholesten-3,B,24,25-triol.

. 5-Cholesten-3B,25,26-triol.

. 5-Cholesten-3B,24,25-triol 3,8,24-dibenzoate.

5-Ch0lesten-3B,24,25-triol 33,24,25-tribenzoate. 25-Trimethylsilyloxy-5-cholesten-3B,24-diol dibenzoate. 

1. 5-CHOLESTENE DERIVATIVES REPRESENTED BY THE FORMULA:
 2. 5-Cholesten-3 Beta ,24,25-triol 3-acetate.
 3. 5-Cholesten-3 Beta ,24,25-triol 3,24-diacetate.
 4. 5-Cholesten-3 Beta ,25,26-triol 3acetate.
 5. 5Cholesten-3 Beta ,24,25-triol.
 6. 5-Cholesten-3 Beta ,25,26-triol.
 7. 5-Cholesten-3 Beta ,24,25-triol 3 Beta ,24-dibenzoate.
 8. 5Cholesten-3 Beta ,24,25-triol 3 Beta ,24,25-tribenzoate.
 9. 25-Trimethylsilyloxy-5-cholesten-3 Beta ,24-diol dibenzoate. 